Bu et al. Lipids in Health and Disease (2017) 16:4 DOI 10.1186/s12944-016-0394-1

RESEARCH

Open Access

Elevated levels of preβ1-high-density lipoprotein are associated with cholesterol ester transfer protein, the presence and severity of coronary artery disease Xiao-min Bu†, Dong-mei Niu†, Jia Wu, Yun-long Yuan, Jia-xi Song* and Jun-jun Wang*

Abstract Background: Preβ1-high-density lipoprotein (preβ1-HDL), plays an important role in reverse cholesterol transport and exhibits potent risk for coronary artery disease (CAD). However, the association of plasma preβ1-HDL and cholesterol ester transfer protein (CETP) levels in CAD patients and the relationship of preβ1-HDL with extent of CAD are debatable. Methods: Preβ1-HDL and CETP levels were measured by enzymed-linked immunosorbent assay (ELISAs) in 88 acute coronary syndromes (ACS), 79 stable coronary artery disease (SCAD) patients and 85 control subjects. The correlation analyses, multiple linear regression analyses and logistic regression analyses were performed, respectively. Results: The preβ1-HDL and CETP levels in ACS patients were significantly higher than those in SCAD patients and both of them were higher than controls’. Preβ1-HDL levels were positively associated with CETP (R = 0.348, P = 0.000), the diameter of stenosis (R = 0.253, P = 0.005), the number of vessel disease (R = 0.274, P = 0.002) and Gensini score (R = 0.227, P = 0.009) in CAD patients. Stepwise multiple linear regression analyses showed that CETP was one of the determinants of preβ1-HDL levels. Logistic regression analysis revealed that elevated preβ1-HDL and CETP were potential risk factors for both ACS and SCAD. Conclusion: The elevated preβ1-HDL levels may change with CETP concentrations in CAD patients and were related to the presence and severity of CAD. Keywords: Preβ1-HDL, CETP, Coronary artery disease, Atherosclerosis

Background Preβ1-high-density lipoprotein (preβ1-HDL), a quantitatively minor high-density lipoprotein (HDL), is formed as nascent apolipoprotein (apo) A-I enters plasma and as a substrate or product in interconversion of HDL species [1]. After receiving free cholesterol effluxed from ATP binding cassette transporter A1 (ABCA1) transporter, it is esterified with a free fatty acid derived from lecithin mediated by lecithin-cholesterol acyl transferase (LCAT) [2, 3]. Cholesteryl esters (CE) are then incorporated into cores of α-HDL, subsuming preβ1-HDL. CE * Correspondence: [email protected]; [email protected] † Equal contributors Department of Clinical Laboratory, Jinling Hospital, School of Medicine, Nanjing University, 305East Zhongshan Rd., Nanjing 210002, China

are transferred from α-high-density lipoprotein into cores of accepter lipoproteins by cholesterol ester transfer protein (CETP) [4]. The preβ1-HDL was shown to be significantly correlated to the high efflux which was mediated by ABCA1 [5]. The fasting preβ1-HDL concentration has been reported elevated in patients with coronary artery disease (CAD), hyperlipidemia, type 2 diabetic, obesity and hemodialysis [6–9]. It is proposed that increased preβ1-HDL may be used as a marker of risk for structural CAD, myocardial infarction (MI) and cerebral vascular disease (CVD) [10]. However, a recent study reported that serum preβ1-HDL levels detected by their new one-dimensional polyacrylamide gel electrophoresis (PAGE) system were negatively associated with severity of CAD [11]. This result needs further

© The Author(s). 2017 Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.

Bu et al. Lipids in Health and Disease (2017) 16:4

validition. Actually, the relationship between preβ1-HDL and CAD is still controversial. CETP, one of decisive factors that determines highdensity lipoprotein cholesterol (HDL-C), mediates the transfer of CE from HDL to low density lipoprotein (LDL), very low density lipoprotein (VLDL), and an exchange of triglyceride (TG). It relates to particle size, lipid composition and function of lipoprotein [12]. CETP also plays a key role in reverse cholesterol transport (RCT) and development of atherosclerosis [13, 14]. Several lines of evidence have shown that incubation of large α-HDL particles with CETP could produce preβ1HDL [6, 7]. which suggested the levels of preβ1-HDL may be associated with CETP. An earlier research performed in transgenic mice indicated that the expression of CETP resulted in an increase in the proportion of apoA-I in the preβ1-HDL fraction and a stimulation of the efflux and esterification of cell-derived cholesterol [15]. However, study has been published to show the relationship of plasma preβ1-HDL and CETP levels in CAD patients. Therefore, this study was undertaken to investigate the associations of plasma preβ1-HDL and CETP in CAD patients, and to further elucidate the clinical values of preβ1-HDL for evaluating the severity of CAD.

Methods Study subjects

A total of 167 admitted CAD patients were randomly enrolled from the Department of Cardiology of Jinling Hospital between January 2014 and March 2015. All the patients were undergoing clinically indicated coronary angiography. Angiograms of all the CAD patients showed at least 50% stenosis in ≥1 coronary artery. 88 patients with acute coronary syndromes (ACS) included acute myocardial infarction patients and unstable angina (UA) with Braunwald classification II or III, who exhibited the positive cardiac biomarkers result [cardiactroponin I (cTnI) > 0.090 ng/ml], acute ischemic-type chest pain (lasting for > 15 min, duration from symptoms onset to emergency admission within 72 h) and characteristic electrocardiogram changes. 79 stable coronary artery disease (SCAD) patients with a normal electrocardiogram and documented normal left ventricular contractility, except for possible minor nonspecific ST-T features, had a minimum 1-year history without any cardiac events/procedures suggestive of ACS. The exclusion criteria of the CAD patients included mild disease of angiography (a stenosis of 10 to 50% of the luminal diameter in all the 3 coronary arteries), prior coronary revascularization, and the presence of renal disease. 85 control subjects selected from routine health examination were found normal in physical and electrocardiography and laboratory tests, and without diseases such as

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hyperlipidemia, hypertension, diabetes mellitus, or any clinical evident sign of atherosclerosis. In patients with ACS, blood samples were taken on admission. Blood samples were collected at least 12 h after fasting from control subjects and patients with SCAD. The blood sample was collected into EDTA (1 mg/ml) containing tube and plasma was promptly separated by a 15 min centrifugation at 3000 rpm, then stored at −80 °C until analysis. This study protocol was approved by the Ethics Committee of Jinling Hospital (REC number: GH23335H) and all the subjects provided written informed consent. Angiographic analysis

Catheterization was performed by either the Sones or the Judkins. Multiple views including angulated views were obtained, and the angiograms were evaluated. The extent of angiographically documented CAD was quantified in the left anterior descending coronary artery, the left circumflex artery, or the right coronary artery as follows: normal coronary arteries (smooth, with either no stenosis or a stenosis of 0.05). 54.5% of ACS and 31.6% of SCAD patients received statin treatment in the present study at the time of sampling. The extent of angiographically documented CAD in the ACS patients was greater than that in SCAD patients (Table 1). Plasma preβ1-HDL, CETP and lipid concentrations in ACS and SCAD patients

Compared with control subjects, preβ1-HDL and CETP levels were found significantly increased in both patients with ACS and SCAD. Furthermore, preβ1-HDL and CETP levels were significantly higher in ACS than those in SCAD (Table 2).

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Table 1 Baseline clinical characteristic, lipid concentrations in the study groups Variable

ACS (n = 88)

SCAD (n = 79)

Control (n = 85)

Age (y)

64.52 ± 12.04

67.42 ± 13.34 63.79 ± 13.17

Male/female

62/26

56/23

64/21

Hypertension (%)

59 (67%)

62 (78%)

0 (0)

Ischemic stroke (%)

32 (36%)

24 (30%)

0 (0)

Diabetes mellitus (%)

39 (44%)

30 (38%)

0 (0)

Statins, n (%)

48 (54.5)

25 (31.6)

0 (0)

ACEI/ARB, n (%)

63 (71.6)

51 (64.6)

0 (0)

Medication

Beta blockers, n (%)

58 (65.9)

42 (53.2)

0 (0)

Aspirin (%)

60 (68.2)

26.2 (21.0)

0 (0)

Maximal stenosis (%)

89.34 ± 15.62**

23.87

-

Number of vessel disease

2.04 ± 0.85

1.14 ± 0.93

-

cTnI, ng/L

19.42 ± 71.19**

0.03 ± 0.02

-

CK-MB, U/L

75.42 ± 126.14** 11.68 ± 4.12

Gensini score

62.23 ± 41.58**

Angiographic analysis

17.20 ± 18.39 -

Data are presented as the mean ± SD or number (%) of subjects Compared with SCAD: *P < 0.05, **P < 0.01

Associations among preβ1-HDL, CETP, other lipid levels and the extent of CAD

To study the relationship of preβ1-HDL, CETP, other lipid parameters and the extent of CAD, Spearman rank correlation analyses were performed. In all the CAD patients, including ACS and SCAD patients, preβ1-HDL were found positively correlated with CETP (r = 0.348, P = 0.000), maximal stenosis (r = 0.253, P = 0.005), number of vessel disease (r = 0.274, P = 0.002), Gensini score (r = 0.227, P = 0.009), TC (r = 0.401, P = 0.000), TG (r = 0.195, P = 0.017) and LDL-C (r = 0.309, P = 0.000); and CETP were positively correlated with number of vessel disease (r = 0.238, P = 0.013), Gensini score (r = 0.282, P = 0.002), TC (r = 0.209, P = 0.016) and LDL-C (r = 0.202, P = 0.023) (Table 3). Table 2 Plasma preβ1-HDL, CETP and other lipid concentrations in ACS, SCAD and control groups Variable

ACS (n = 88)

SCAD (n = 79)

TC(mmol/L)

4.68 ± 1.34 **

Control (n = 85)

4.16 ± 1.10 **

4.62 ± 0.58

TG(mmol/L)

2.04 ± 1.47

1.70 ± 1.31

1.09 ± 0.41

HDL-C(mmol/L)

0.99 ± 0.23**

1.13 ± 0.72**

1.31 ± 0.25

*

LDL-C(mmol/L)

2.91 ± 1.02

Preβ1-HDL(μg/L)

36.24 ± 17.03**,#

CETP (mg/L)

**,##

3.42 ± 1.80

Compared with control: *P < 0.05; **P < 0.01 Compared with SCAD: #P < 0.05; ##P < 0.01

*

2.88 ± 0.85

2.45 ± 0.81

24.68 ± 21.02**

7.44 ± 5.49

*

2.05 ± 1.10

1.52 ± 0.98

Bu et al. Lipids in Health and Disease (2017) 16:4

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Table 3 Spearman rank correlations between preβ1-HDL, CETP and other variable in CAD patients Variable

Preβ1-HDL

Table 5 Logistic regression analysis of risk factors for ACS and SCAD

CETP

**

Preβ1-HDL *

P value

OR(95%CI)

P value

1.161 (1.107–1.219)